Large-Area GeSe Realized Using Pulsed Laser Deposition for Ultralow-Noise and Ultrafast Broadband Phototransistors
Sheetal Dewan, Prabal Dweep Khanikar, Richa Mudgal, Avneet Singh, P. K. Muduli, Rajendra Singh, Samaresh Das
Abstract
Here, we report on the comprehensive growth, characterization, and optoelectronic application of large-area, two-dimensional germanium selenide (GeSe) layers prepared using the pulsed laser deposition (PLD) technique. Back-gated phototransistors based on few-layered 2D GeSe have been fabricated on a SiO 2 /Si substrate for ultrafast, low noise, and broadband light detection, showing spectral functionalities over a broad wavelength range of 0.4–1.5 μm. The broadband detection capabilities of the device have been attributed to the self-assembled GeO x /GeSe heterostructure and sub-bandgap absorption in GeSe. Besides a high photoresponsivity of 25 AW –1, the GeSe phototransistor displayed a high external quantum efficiency of the order of 6.14 × 10 3 %, a maximum specific detectivity of 4.16 × 10 10 Jones, and an ultralow noise equivalent power of 0.09 pW/Hz 1/2 . The detector has an ultrafast response/recovery time of 3.2/14.9 μs and can show photoresponse up to a high cut-off frequency of 150 kHz. These promising device parameters exhibited by PLD-grown GeSe layers-based detectors make it a favorable choice against present-day mainstream van der Waals semiconductors with limited scalability and optoelectronic compatibility in the visible-to-infrared spectral range.